Quality Tests for Milk and Milk Products

Dairy products are a rich source of food, and with modern advancements, the shelf life is no longer a few hours or day. The products can be shipped globally owing to the processing that preserves the products. You might be tempted to think that this erodes the need to maintain high-quality standards, as the products can be processed and packed. That’s far from the truth, and in today’s market, dairy testing to ascertain that only quality milk makes it to the processing is a lot more critical than before. From production, transportation, and processing, high-quality standards have to be observed to ensure that consumers receive healthy products. The best part is that with the advancements, stakeholders now understand a lot that makes testing more comfortable and reliable. Let’s look at some quality tests for milk and milk products shaping the field.

Table of Contents

Preliminary tests

These are initial tests carried out to determine if the milk is fit for processing. They are simple, including organoleptic and chemical tests. Organoleptic tests consider the milk color, smell, and temperature. To undertake the test, your sense of smell, touch, and sight must be good, as that’s the basis of identifying if the milk can proceed to the next test. From the milk can, you’ll tell how well it was handled, and if foreign objects, foul smell, and unusual colors are spotted, then the milk can’t be accepted for processing.

After the sense-based tests, simple chemical tests follow. A sample of milk is boiled in a test tube, aimed at spotting any signs of coagulation. This test tells you if the milk can withstand processing, and if it is determined that it is too acidic, it is deemed unfit. If it isn’t too sour, the next step is the alcohol test.

At 72% ethanol concentration, alcohol is mixed with an equal amount of milk, further establishing the acidity levels. For better accuracy, alizarin, a dye whose color changes following the acidity level, is added.

The test could either result in red-brown color, yellowish-brown, yellow, or pale red/lilac. The color establishes that the milk is normal, slightly acidic, acidic, or alkaline, respectively. An additional alcohol test at 80% ethanol concentration is then carried out. The test, using an alcohol gun, establishes if the milk has stable protein to withstand pasteurization. If the mixture clots, it can’t be subjected to heat treatment as it can’t withstand the process. 

Confirmatory tests

Now that you’ve established that the milk can withstand processing conditions, it is time for more focused tests. The Lactometer test is the first confirmatory test, and it is based on the fact that milk has a higher density than water. The test establishes if the milk has been adulterated either with other solids or water. Resazurin test then follows, establishing the quality of your bulk milk, and at this point, you can proceed with processing. However, you could also include lab tests such as titration, helping you monitor storage, and control manufacturing processes.

Quality tests are essential as they guide the processes, from storage, manufacturing, packaging, and distribution. With a little bland of poor quality, the whole batch could be ruined, stressing the need to employ due diligence and ensure that only quality milk makes it to the processing.